package org.sbbs.security.utils;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.Hex;
import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.commons.lang3.Validate;

public class Encodes {
	  private static final String ALPHABET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

      private static final String DEFAULT_URL_ENCODING = "UTF-8";

      private Encodes() {
      }

      /**
       * Hex编码, byte[]->String.
       */
      public static String encodeHex(byte[] input) {
              return Hex.encodeHexString(input);
      }

      /**
       * Hex解码, String->byte[].
       */
      public static byte[] decodeHex(String input) {
              try {
                      return Hex.decodeHex(input.toCharArray());
              } catch (DecoderException e) {
                      throw new IllegalStateException("Hex Decoder exception", e);
              }
      }

      /**
       * Base64编码, byte[]->String.
       */
      public static String encodeBase64(byte[] input) {
              return Base64.encodeBase64String(input);
      }

      /**
       * Base64编码, URL安全(将Base64中的URL非法字符'+'和'/'转为'-'和'_', 见RFC3548).
       */
      public static String encodeUrlSafeBase64(byte[] input) {
              return Base64.encodeBase64URLSafeString(input);
      }

      /**
       * Base64解码, String->byte[].
       */
      public static byte[] decodeBase64(String input) {
              return Base64.decodeBase64(input);
      }

      /**
       * Base62(0_9A_Za_z)编码数字, long->String.
       */
      public static String encodeBase62(long num) {
              return alphabetEncode(num, 62);
      }

      /**
       * Base62(0_9A_Za_z)解码数字, String->long.
       */
      public static long decodeBase62(String str) {
              return alphabetDecode(str, 62);
      }

      private static String alphabetEncode(long num, int base) {
              num = Math.abs(num);
              StringBuilder sb = new StringBuilder();
              for (; num > 0; num /= base) {
                      sb.append(ALPHABET.charAt((int) (num % base)));
              }

              return sb.toString();
      }

      private static long alphabetDecode(String str, int base) {
              Validate.notBlank(str);

              long result = 0;
              for (int i = 0; i < str.length(); i++) {
                      result += ALPHABET.indexOf(str.charAt(i)) * Math.pow(base, i);
              }

              return result;
      }

      /**
       * Html 转码.
       */
      public static String escapeHtml(String html) {
              return StringEscapeUtils.escapeHtml4(html);
      }

      /**
       * Html 解码.
       */
      public static String unescapeHtml(String htmlEscaped) {
              return StringEscapeUtils.unescapeHtml4(htmlEscaped);
      }

      /**
       * Xml 转码.
       */
      public static String escapeXml(String xml) {
              return StringEscapeUtils.escapeXml(xml);
      }

      /**
       * Xml 解码.
       */
      public static String unescapeXml(String xmlEscaped) {
              return StringEscapeUtils.unescapeXml(xmlEscaped);
      }

      /**
       * Csv 转码.
       */
      public static String escapeCsv(String csv) {
              return StringEscapeUtils.escapeCsv(csv);
      }

      /**
       * Csv 解码.
       */
      public static String unescapeCsv(String csvEscaped) {
              return StringEscapeUtils.unescapeCsv(csvEscaped);
      }

      /**
       * URL 编码, Encode默认为UTF-8. 
       */
      public static String urlEncode(String part) {
              try {
                      return URLEncoder.encode(part, DEFAULT_URL_ENCODING);
              } catch (UnsupportedEncodingException e) {
                      throw Exceptions.unchecked(e);
              }
      }

      /**
       * URL 解码, Encode默认为UTF-8. 
       */
      public static String urlDecode(String part) {

              try {
                      return URLDecoder.decode(part, DEFAULT_URL_ENCODING);
              } catch (UnsupportedEncodingException e) {
                      throw Exceptions.unchecked(e);
              }
      }
}
